Machine for making well screens from metallic tubes



June 13,1933. E. E. JOHNSON 1,913,760

MACHINE FOR MAKING WELL SCREENS FhOM METALLIC TUBES Filed Oct. '7, 19296 Sheets-Sheet 1 Inventor: EEJZa/msen. By M l fl ii'orrzeys .11. WP at JJ NW I v r II- E g l mm m ww W m [I on June 13, 1933. E. E. JOHNSONMACHINE FOR MAKING WELL SCREENS FROM METALLIC TUBES Filed Oct. '7, 19296 Sheets-Sheet 2 y M 1T s wk 9 v a m 2 r M o 1T T NQ- 0N. OW. IV; I munJwNN vmT I, 1 92 NN I I i I l I I I I l I I I I l I l I l l l l.LPHHHHIH IIHI IH m mm m I. \I o I I m I .0 ou-\ wr r: 9 3w Al m I June13, 1933. E.AE. JOHNSON MACHINE FOR MAKING WELL SCREENS FROM METALLICTUBES Filed OQt. 7', 1929 -e Sheets-Sheet 5 /36 In ven for:

EB Jb/znson, 9 w M {tier/legs June 13, 1933. E. E. JOHNSON MACHINE FORMAKING WELL SCREENS FROM METALLIC TUBES 1 Filed Oct. 7, 1929S-Sheets-Sheet 4 In verz for. EL? Jbhnson. M1 N/ June 13, 1933. E,JOHNSON 1,913,760

MACHINE FOR MAKING WELL SCREENS FROM METALLIC TUBES Filed Oct. '7, 19296 Sheets-Sheet 5 Inventor: =EZTJb/mson.

ti'ornegs.

I June 13, "1933. E. E. JOHNSON MACHINE FOR MAKING WELL SCREENS FROMMETALLIC TUBES Filed Opt. 7, 1929 s Sheets-Sheet 6 lh'i/en for. .E. E.(75hr: son By W Patented June 13, 1933 'fiTATES EDWARD E. JOHNSON, OFST. PAUL, MINNESOTA, ASSIGNOR .TO EDWARD E. JOHNSON,

' INCORPORATED, OF ST. PAUL, MINNESOTA, A CORPORATION MAGHINEFOR MAKINGWELL SCREENS FROM METALLIC TUBES Application filed. October 7, 1929.Serial No. 397,878.

I My invention relates to machines for making well screens from metallictubes. An. obect of the invention is to provide a machme which willoperate upon a cylindrical metalall times between the tube and the tapal-.

though the latteris collapsed at intervals to produce an interruptedthread of predetermined form. In the construction particularly shown anddescribed herein, five slots separated by five uncut portions compriseone turn of the helix, and the uncut portions or posts extendinglongitudinally of the tube give it adequate strength. It is obvious thatthe number of slots per turn and hence the number of posts may be variedto suit tubes of different diameters by suitable changes of n gearing inthe machine. In theembodiment here shown, the tube to be operated on isclamped to the head spindle of the machine and caused to move forward ina helical path by means of a stationary lead screw and past a tap whosech asers are alternately advanced and retracted in a path transverselyof the thread being cut, the timing arrangement being such that aninterrupted thread of any determined pattern may be produced.

A particular object of the present invention is to improve upon themachine disclosed and claimed in my prior Patent No. 1,586,311 issuedMay 25, 1926, by providing a cutting device which taps an interruptedthread to the proper depth progressively so that the cutting eifort'isdistributed fairly over all the cutting edges without causing unduestrain on any, each tooth of each chaser acting successively in eachgroove cut. The simultaneone action of the chasers in the periphery ofthe tube serves to minimize the ill efiect of tuhes that are out ofround.

The full objects and advantages of my invention will appear inconnectionwith the so detaileddescription thereof and the novel features of myinventive idea will be particularly pointed out in the claims. r

In the accompanying drawings which illustrate a practical form ofconstruction in which my invention may be embodied, Fig. 1 is a top planView partly in section of the rear portion of the machine. Fig. 2 is atop plan view of the front portion of the machine. Fig. 3 is a view insection on the line 3-3 of Fig. 1. Fig. 4 is a reduced front elevationalview of the machine. Fig. 5 is aview in section on the line 5 5 of Fig.2. Fig. 6 is a view in section on the line 66 of Fig. 5. Fig. 7 is anenlarged sectional View of the head of the machine with the saw andchasers out of engagement with the tube. Fig. 8 is a view correspondingto Fig. 7 with the saw and Chasers engaged with the tube. Fig. 9 is across sectional View of a tube having five slots per turn out therein;Fig. 10 is a view in section on the line 1010 of Fig. 7 Fig. 11 is aView in section on the line 1111 of Fig. 7. Fig. 12 is a view in sectionon the line 12-12 of Fig. 7. Fig. 13 is a plan view of the tap. Fig. 14is a side elevational view of the rear 75 portion of the machine. Fig.15 (Sheet 2) is a View in cross section of a tube having six slots perturn out therein.

Referring to the drawings, it will be understood from Fig. 1 that a tank16 is provided near the rear of the machine, while from Fig. 2 it willbe understood that a tank 18 is provided toward the front of themachine. These tanks in effect constitute suports for the operatingmechanism of the machine. As will be understood from Fig. 4, the bottomsof the two tanks are secured to inverted U-bars 20 which rest upon thefloor. The two tanks are connected by a horizontal angle beam 22 whichextends out beyond the front tank 18 as shown in Fig. 2. A shelf 24 issecured to the rear tank 16 as best shown in Fig. 4 and serves as asupport for an electric motor 26 which is driven from any suitablesource of electricity. Secured to the end of the shaft 28 of this motoras shown in Fig. 1,

' there is a large pulley 30 which is connected by a belt 32 with apulley 34 carried by a shaft 36 which, as will be understood from Fig.4, extends into the tank 16 and drives a pump located therein. This pumpwhich it is not necessary to refer to in detail is of ordinaryconstruction and serves to pump coolin g agent from the tank 16 for apurpose which will be referred to later. Also secured to the motor shaft28, as will be understood from Fig. 4, there is a small pulley 38 whichis connected by a belt 40 with a pulley 42 secured to a shaft 44 mountedin bearings 46 carried by brackets 48 supported from the beam 22, thefront portion of this shaft being mounted in a bearing 49 supported asshown in Fig. 5 by a bracket 51. As shown in Fig. 1, a small gear 50secured to the rear end of the shaft 44 meshes with a large gear 52secured to a shaft 54 mounted in bearings 56. Secured to the rear end ofthe shaft 54 adjacent the gear 52 there is a cam wheel 58 containing acam groove 60 in which rides a roller 62 which, as shown in Fig. 14, ismounted on the upper end of a swinging arm 64, having a pivot 66 at itslower end. A second swinging arm 68, having a pivot 70 at its lower end,is connected to the arm 64 by toggle links 72 and 74, having acommonpivot 76. The reduced upper end of a rod 78 extends through the commonpivot 76. The lower end of the rod 78 is threaded through a hole formedin a support 80 carried by the bar 22. The rod 78, below its support 80,is provided with lock nuts 82 and 84 and at its lower end is providedwith a cross pin 86 by w iich it may be turned when the lock nuts areloosened. By turning the rod 78, the relative positions of the arms and68 are adjusted. for a purpose which will appear later. When the rod 78is screwed upwardly, the upper ends of the arms 64 and 68 are separatedfurther from each other and vice versa. The upper end of the arm 68 istwisted so as to provide a flat portion at right angles to the flat bodyportion of this arm, and said upper end is provided with a hole throughwhich a rod 88 passessiidably and is provided at its rear end withadjustable nuts 90. The rod 88 is intermediately threaded to receive anut 92, while a coiled spring 94 is interposed between the arm 68 and.no nut 92. Forward swinging movement of the arm 68 is imparted to therod 88 through the spring 94 so that the r d is urged forwardly underresilient action. On the return movement of the arm 68, it engages theadjustable nuts and positively retracts the rod 88. This rod 88 passesthrough a stuffing box 96 and is weld-ed or otherwise secured to therear end of a tubular rod 98 which is slidably mounted in a tube 100,having the stuiiin g box 96 secured to the rear end thereof.

The tube 100 is externally threaded as a lead screw for the greaterportion of its length for a purpose which will presently appear, and itis fixedly secured near its rear end in a support 102 carried by the bar22. A split nut device is adapted to engage the threads of the tubularlead screw 100. As

' extensions are adapted to be held in such engagement by a sleeve 118slipped thereover. The open center member 112 is threaded upon thereduced end of a tubular member 120 slidable on the lead screw 100, theother end of the member 120 being provided with an outwardly extendingannular flange 122. A changeable sleeve 124 is secured to the flange 122by set screws 125 while the rear end of the tube T to be operated uponis secured to said sleeve by set screws 127. Upon opening the split nut,it is obvious that this member and the parts connected therewith may beslid to any desired position along the lead screw 100 according to thelength of the tube T which is to be provided with grooves.

Two gears 126 and 128 of different size are secured to the tubularmember 120, while the latter member is rotatable in a sleeve 130 formedat one side of a head casting 132 having a sleeve 134 at its other sideslidably surrounding the shaft 54. The head casting 132 has an angularshoe 135 adapted to slide on the beam 22 as will be understood from Fig.3. A plate 136 is secured to the sleeve 134 by a screw bolt 137 passingthrough a slot in the plate so that the latter may he slid along akeyway when the bolt 137 is loosened. The plate 136 carries a flange 138whose distance from the sleeve 134 may be varied in the manner juststated. A gear 140, which is feathered on the shaft 34, is held back ofthe flange 138 so as to be out of mesh with the gear 128 when themachine is set in the manner shown in Fig. 1. At the same time, a gear142 which is slightly larger than the gear 140 and is also feathered onthe shaft 54 engages the front of the flange 138 so as to he in meshwith the gear 126 and thereby rotate the latter. In order to change thegear ratio, the gear 142 is moved out of mesh with the gear 126, whilethe gear 140 is moved into mesh with the gear 128. This may be readilydone upon loosening the bolt 137, it being understood that the gears 140and 142 are mounted together on a sleeve 143. As will be seen from Figs.7 and 8, the front end of the lead screw 100 is provided with internalthreads to receive external threads formed on the reduced rear end 144of a collapsible tap 146. The exterior of the tap is provided with aplurality of longitudinal grooves which receive ohasers 148 which attheir rear ends are pivotally mounted on pins 150. In

the embodiment hereinshown, there are five of these chasers comprisingthe tapping mechanism, of the same pitchas the lead screw and equallyspaced around the head. Each of the chasers 148 is provided with aplurality of cutting teeth or edges 152 which are progressively longertoward'the front so as to form internal grooves of the proper depth inthe tube T by a progressive tapping action by each tooth of each chasercutting succesively in each groove. The'tap when in action will ofcourse follow its own lead, but when retracted as is necessary atintervals in cutting an interrupted thread, it is kept in properposition to enter the next succeeding cut by the lead screw 100. Theinner surfaces of the chasers 148 are intermediately provided withinclined'surfaces 154, while their outer ends are provided with externalinclined surfaces 156, these two sets ofinclined surfaces being for apurposewh'ich will now be explained.

The body of the tap 146 is chambered centrally to diameters 159, 157 and165 to receive and support the stem 158 and chaser cams 155 and 164 forthe reciprocation as will presently be explained. The stem 158 extendsforwardly through the chambers 159,

157 and 165 and is formed intermediately' with a male cam or cone 162adapted to engage and support the inclined surfaces 154 of the chasers148 on their outward or cutting stroke. The forward end of the stem 158is threaded to'the member 164 which is adapted to slide in the chamber165 and is maintained in its proper adjustment on the stem by a checknut 166 abutting the end thereof. The member 164 is provided with afemale cam o-r cone 168 adapted to engage the surfaces 156 of thechasers 148 on their inward or idle stroke. It will be understood thatwhen the stem 158 is moved forwardly by the action of thecam 58 into theposition shown in Fig. 8, the male cone 162 will force the cutting teeth152into engagement with the inner surface of the tube T, and when thecam retracts the stem 158 into the position shown in Fig. 7, the cuttingteeth will be with drawn from engagement with the tube T. The cuttingteeth do not ordinarily out quite through the tube, and, therefore, inorder to complete the cut'so as to form the helical slots, a saw 170 isprovided for operating upon the exterior of the tube coincident with theinterior cuts. This saw is secured to shaft 172 in well-known manner,this shaft having secured thereto a pulley 174 driven by a belt 176 froma pulley 17 8 secured to the shaft 44. The shaft 172' is rotatablymounted in bearings 180 and 182 carried by a-swinging frame 184. Tosupport this frame, a bracket 186secured to the beam 22 is provided withspaced lugs 188 and 190 which have threaded holes for receiving screwbolts 192 and 194 having pointed ends received in recesses in I theframe 184 so that the latter may rock.

The bracket 186 carries outstanding ears 196 between which a curvedlever 198is pivoted. The swinging frame 184 is adjustably attached tothe outer end of the lever 198 by I a screw bolt200 which passes throughthe lever and threads into the frame. A screw bolt'202 which threadsthrough this lever into engagement with the frame serves to inengagement with the lever 198, the saw 17 O V will be swung out ofengagement with the tubeT, and when the low portion of the cam is inengagement with this lever, the saw willmove into engagement with thetube T so as to make a cut therein. .It will-be noted fromFig. 6, thatthe shaft 172 is somewhat inclined so that the saw 170. makes itscutwith the same angle of inclination as the rooves which are formed by thecutting teeth of the tap. Byreferring to Figs. 7 and 8, it will be seenthat the saw 170 makes its out shortly after the grooves made by the taphave been cut by the tapping action nearly through the tube T. V

The following device is provided to automatically'stop the feeding ofthe tube when it, has been provided with grooves extending nearly to itsrear end. The shaft 44 is provided with a clutch 206 of ordinaryconstruction normally held in clutched position and which, as shown inFig. 1, is located between the pulley 42 and the gear 50 so that whenthe clutch is disengaged, rotation of the gear 50 is discontinued. Themovable member of the clutch. is engaged by a shifter yoke 208 attachedto the upper end ofan arm 210 whose lower end is pivoted between earscarried by the shelf 24 as shown in Fig. 4. Theyoke 208 is continuedupwardly in the form of an arm 212 whose upper end is connected by aclutch throw-out rod 214 with the upper end of a lever 216 which isintermediately pivoted to a supporting member.

218 secured to the bracket 51. The lower arm of the lever 216 extendsdown into the path of the angularv shoe 135 which constitutes partof thecasting 132 whichas previously indicated advances with the split nutmembers 104 and 106 as the tube T is being fed forwardly. vWhen the rearend of the tube T has nearly reached the cutters, the. shoe 135 comesinto engagement with the lower end of the lever 216 and forces the rod214 rearwardly,'thereby disconnecting the clutch and stopping thefeeding movement of the tube T. As shown in Figs. 2 and 6, the rod 214is resiliently actuated by the lever 216 through the intervention of acoiled spring 220 interposed between the lever and a collar 222 securedto the rod 214, it being noted that the rod 214, after passing through ahole in the upper end of the lever 216, is provided with a collar 224.The tap 146 has been shown as provided with live chasers whereby thetube T is provided with live spiral grooves per turn in the form shownin F ig. 9. It is obvious from an inspection of Figs. 7 and 8 that thetap may be readily removed and replaced by another tap of different sizeand having a different number of chasers. Fig. 15 shows a larger tube Twhich has six spiral grooves per turn. It is obvious that for thispurpose, a tap having six chasers would be provided. By referring toFig. 1, it will be understood that the sleeve 124 may be readilyreplaced by another sleeve of such shape that the rear end of a tube ofdifferent size may be secured in place.

In order to support the tube T for its combined rotary and longitudinalmovement, a number of guides 226 are secured to the beam 22 as shown inFig. 2. These guides carry removable cylindrical members 228 in orderthat tubes of different sizes may be supported. As before .stated, thecasting 132 carries a shoe 135 which rests slidably upon the beam 22. Inorder to additionally support this casting and the parts which movetherewith, the casting is provided with a gib 230 as shown in Fig. 3which engages with a guide bar 232 secured to the beam 22 in spacedrelation thereto by studs 234. The pump in the tank 16, which waspreviously referred to as being driven by the shaft 36, is connected toa delivery pipe 236 provided with a shutoff valve 238. The upper end ofthe pipe 236 connects with the inner portion of the stuffing box 96 sothat cooling agent forced by the pump is delivered into the interior ofthe threaded tube 100 through which it passes into the tap 146 which isprovided with openings 240 through which the coolant passes to thecutting teeth and to the tube as it is being cut. The stream of coolantserves also to carry away the cuttings from the tapping operation. Thecupshaped member 164 is also provided with openings 242 through whichsome of the coolant may escape. By referring to Fig. 2, it will beunderstood that the coolant, after having served its purpose, runs intothe front tank 18. It is apparent that this tank may be provided with ascreen to catch chips of metal so that they will be prevented fromfalling down into the tank. From a point near the upper end of the tank18, a return pipe 244 leads back to the bank 16, this pipe beingdownwardly inclined as will be understood from Fig. 4 so that thecoolant flows back by gravity.

The operation and advantages of my invention will be understood inconnection with the foregoing description. With the machine set as shownin Fig. 1, rotation of the shaft 54 acting through the meshed gears 126and 142 causes rotation of the tubular member 120 and the sleeve 124 towhich the tube T is secured. The tubular member 120 also carries thesplit nut device which is rotated thereby, and the rotation of thisdevice by its engagement with the threaded tube 100 causes the tube T tobe fed forwardly or longitudinally so that this tube is given a combinedrotative and longitudinal movement. At the same time, the cam wheel 58secured to the shaft 54 is caused to rotate and thereby reciprocate therod 98 and the attached stem 158 which passes slidably through the tap146. When the stem 158 moves forwardly, the cone 162 moves along theinclined surfaces 154 of the chasers 148 and causes the cutting teeth152 to bite into the interior surface of the rotating forwardly movingtube T as shown in Fig. 8 with the result that the teeth 152 will cuthelically extending grooves or slots. Since the cone 162 is movedforwardly under the resilient action of the spring 94, the chasers arecaused to engage the tube T without shock. Furthermore, if the tube T isnot truly cylindrical, the simultaneous action of the chasers serves tominimize the effect of such eccentricity and produce satisfactoryresults in operation. When the stem 158 moves backwardly, the cone 162is retracted and the cup member 168 engages the inclined surfaces 156 onthe chasers 154 and removes the cutting teeth from engagement with thetube as shown in Fig. 7. As previously indicated, the extent of thisretracted movement may be regulated by turning the rod 78 to vary theinclination of the links 72 and 74 and hence the position of the arm 68relative to the arm 64. It will also be understood that the nuts 90 and92 are to be adjusted so as to secure proper action of the chasers. Itis apparent from Fig. 14 that the high left hand portion of the cam 58extends for a much greater distance peripherally than does the highright hand portion thereof, and hence the period of engagement of thecutting teeth with the tube T is much greater than their period ofdisengagement therefrom. Since the gears 142 and 126 have a ratio of oneto five, there will be five slots per turn of the tube when these gearsare in mesh. The gears 140 and 12 8 have a ratio of one to six, and,hence, when these gears are brought into mesh. there will be six slotsper turn of the tube, it being understood that a tap having six chasersis then substituted for the one having five.

It is apparent from Fig. 8, that the cutting action of the teeth 152 isin the nature of a tapping action since the out first made by ashorttooth is followed by a deeper cut made by a longer tooth and so onprogressively until the longest tooth of each chaser has operated in thegroove which is being cut. It is to be noted that the sets of cuttingedges on I with relation to the tube.

, 3-. A machine for making well screens from metallic tubes comprisingatapping cutter the respective chasers follow each other during theoperation of the machine in such manner as to produce a progressivelyincreasing depth of cut by the helical forward travel of the tube andthe'overlapping relation of the sets of cutting edges. The cuttingedgesare not made to cut entirely through the wall of the tube, and the saw170 operates to complete the slot by cutting from the outside of thetube into the slots or grooves which have just beenformed by the tappingteeth 152 so that spirally extending slots are produced piercingentirely through the wall of the tube. The effect of the saw is toproduceslots having a uniform width on the exterior of the tuberegardless of variations in the thickness of the wall ofthe tube. Byreferring to Fig. 5, it will be understood that the position of the sawmay be readily adjusted to suit the size of the tube which is to be cut.Change of the gear ratio betweenthe shaft'54 and the tubular member 120rotated thereby does not affect the length of cut made by the saw, andit will be understood that the cam 204 which swings the saw will be setso that the' saw enters at the beginning of an internal groove andleaves at the end of this groove. I In order to change the length of cutmade by the saw, it is only necessary torun the saw to greater or lessdepth of cut. The pump supplies a constant stream of coolant to thecutting teeth and saw so that overheating of these parts is prevented.The coolant-may consist of any liquid suitable for this purpose whichcan be circulated by the pump. v v

,I' claim: r 1. A machine for making well screens from metallic tubescomprisingatapping cutter,

means for giving the tube and said cutter a relative combined rotativeandlongitudinal movement, means for causing said cutter; and

vtube to alternately approach and recede with relation to each other toproduce asuccession of helically extending cuts in the wall of the tube,a saw, and mechanism for causing said saw to operate in said cuts. c 2.'A machine for making well screens from metallic tubes comprising atapping-cutter, means for giving the tube a combined rotative andlongitudinal movement, means for causing said cutter to alternatelyadvance and recede with relation to said tube topro duce a succession ofhelically-extending cuts in the wall of the tube,'a saw positioned tooperate in said cuts, and means for causing said sawtoalternatelyadvance and recede positioned to I operate upon the inside ofthe tube, means for giving the tube a combined rotative and longitudinalmovement,

means for causing said cutter to alternately advance and recede withrelationto said tube to produce a succession of helically'extendi'ng thetube, and means for causing said saw to alternately advance and recedewith relation to the tube. V

' 4. A machine for making well screens from metallic tubes comprising adriven shaft, a stationary externally threaded cylindrical member, a nutmember adapted to engage said cylindrical member, means for holding thetube for movement with said nut member, changeable speed gearing betweensaid driven shaft and nut member whereby they tube may be given. acombined rotative and longitudi nal movement at different speeds, atapping cutter, and means for causing said cutter to alternatelyapproach and recede with relation to the tube to, produce a successionof helically extending separated cuts in the wall thereof. 1

5. A machine for making well screens from metallic tubes comprising adriven shaft, a stationary leadscrew, a nut adapted toengage said leadscrew, means for holdingthe tube for movement with saidnut, gearingbetween said driven shaft and said nut whereby the tube may be given acombined rotative and longitudinal movement, a tapping cutter, and meansfor'causing said cutter to 'alternately approach and recede withrelation to the tube to produce a succession of helically extendingseparated cuts in the wall thereof. 3'

Y 6. A machine for making well'screens from metallic tubes comprising adriven shaft, a stationary externally threaded cylindrical member, anutmember adapted to engage said cylindrical member, means for holdingthe tube for movement with said nut member, a plurality of differentsized gears any one of which is adapted to rotate said nut member togive the tube a combined rotative and longitudinal movement, a pluralityof different sized gears feathered on said drivenshaft and held forlongitudinal movement with said nut member, means whereby any one ofsaid last mentioned gears maybe made to mesh with the corresponding oneof said. first mentioned gears to change the gear-ratiO acutting device,and means for causing said cutting device to alternately approach andrecede with relation to the tube means for rotating-said nut member fromsaid shaft whereby'the tube is given a combined rotative andlongitudinal movement, a cutting device, and means for causing saidcutting device to alternately approach and recede with relation to thetube to produce a succession of helically extending cuts in the wallthereof.

8. A machine for making Well screens from metallic tubes comprising adriven shaft, operating connections between said shaft and the tube forgiving the latter a combined rotative and longitudinal movement, atapping cutter, means for causing said cutter to alternately approachand recede with relation to the tube to produce a succession ofhelically extending cuts in the wall thereof,

a clutch on said driven shaft normally in clutched pos1t1on,and meansfor automatically disengaging said clutch when the cutting of the tubeis completed.

9. A machine for making well screens from metallic tubes comprising adriven shaft, a stationary externally threaded cylindrical member, a nutmember adapted to engage said cylindrical. member, means for holding thetube for movement with said nut member, means for rotating said nutmember from said shaft whereby the tube is given a combined rotative andlongitudinal movement, a cutting device, means for causing said cuttingdevice to alternately approach and recede with relation to said tube toproduce a succession of helically extending cuts in the wall thereof, aslide mounted to move longitudinally with said nut member, a clutch onsaid driven shaft normally in clutched posi tion, and a clutch throw-outdevice operated by said slide when the cutting of the tube is completed.

10. A machine for making well screens from metallic tubes comprising afront tank, a rear tank in spaced relation thereto, a beam supported bysaid tanks, means supported by said beam for giving the tube a combinedrotative and longitudinal movement, a cutting device located above saidfront tank, means for causing said cutting device to alternately advanceand recede with relation to the tube to produce a succession ofhelically extending cuts in the wall of the tube, a device for pumpingcooling agent from said rear tank for delivery to said cutting device,and a gravity connection between said front and rear tanks for carryingback to said rear tank the cooling agent which has passed said cuttingdevice.

11. A machine for making well screens from metallic tubes comprisingmeans for giving the tube a combined rotative and longitudinal movement,a cam, a swinging arm engaged by said cam for rocking movement thereby,a second swinging arm, an adjustable connection between said arms, a rodattached to said second arm for reciprocation thereby, and a cuttingdevice operated by said rod for causing the cutting device toalternately approach and recede with relation to the tube to produce aseries of helically extending cuts in the wall thereof.

12. A machine for making well screens from metallic tubes comprisingmeans for giving the tube a combined rotative and longitudinal movement,a cam, a swinging arm engaged by said cam for rocking movement thereby,a second swinging arm, an adjustable connection between said arms, a rodhaving one of its ends passing slidably through the free end of saidsecond arm, an enlargement on said end, a spring resiliently holdingsaid second arm in engagement with said enlargement, a cutter headassociated with the other end of said rod, and a cutting device carriedby said cutter head and caused by reciprocation of said rod toalternately approach and recede with relation to the tube to produce asuccession of helically extending cuts in the wall thereof.

13. A machine for making well screens from metallic tubes comprisingmeans for giving the tube a combined rotative and longitudinal movement,a cutter head, a plurality of tapping cutter arms pivotally mounted atone end around said head, said arms having inner and outer inclinedsurfaces, a reciprocating rod extending slidably through said cutterhead, a cone member carried by said rod and which during forwardmovement thereof moves on said inner surfaces to cause the cutters toengage the tube, and a cuplik-e member carried by 7 said rod having aninterior inclinedsurface which during reverse movement of said rodengages said outer inclined surfaces to retract said cutters.

14. In a machine for producing interrupted threads in metallic tubes, acollapsible tapping cutter, means for giving the tube and said tappingcutter a relative rotative movement, and means for alternatelycollapsing and expanding said tapping cutter to produce a succession ofhelical cuts in the wall of the tube.

15. In a machine for producing interrupted threads in metallic tubes, acollapsible tapping cutter, means for giving the tube and said tappingcutter a relative combined rotative and longitudinal movement, and

means for alternately collapsing and expanding said tapping cutter toproduce a succession of helical cuts in the wall of the tube.

16. In a machine for producing interrupt ed threads in metallic tubes, acollapsible tapping cutter, means for giving the tube a combinedrotative and longitudinal movement, and means for alternately collapsingand expanding said tapping cutter to produce a succession of helicalcuts in the wall of the tube.

17. In a machine for producing interrupted threads in metallic tubes, acollapsible 1 tapping cutter, means for giving the tubes a combinedrotative and longitudinal movement, and a cam for causing said tappingcutter to be alternately collapsed and expanded to produce a successionof helical cuts in the wall of the tube, said cam being so shaped that aperiod of engagement of said tapping cutter with the tube is greaterthan its period of disengagement therefrom.

-18. In a machine for producing interrupted threads in metallic tubes, acollapsible tap having a plurality of chasers each with a plu- V ralityof thread-cutting edges, means for giving the tube and said tap arelative rotative movement, and means for alternately collapsing andexpanding said tap for causing said edges to produce a succession ofhelical cuts in the wall of the tube.

19. In a machine for producing interrupted threads in metallic tubes, afixed lead screw adapted to beenveloped by the tube, a

travelling head engaging said lead screw for I movement thereby andcarrying the tube, a collapsible tapping cutter carried by the free endof said lead screw, and means for alternately collapsing and expandingsaid tapping cutter to produce a succession of helical cuts in the wallof the tube.

In testimony whereof I hereuntoaflix my 1 signature.

EDWARD E. JOHNSON.

